In recent years, biologic agents such as infliximab, vedolizumab, and ustekinumab have demonstrated tremendous potential in the treatment of inflammatory bowel disease (IBD), altering the traditional treatment paradigm for IBD. Despite their significant efficacy, there remains a subset of patients who do not respond to biologic agents, necessitating research into the response mechanisms of biologic therapy to explore more precise treatment strategies. Preliminary work by the principal investigator has identified multiple potential responder cell subtypes to biologic agents, which may be influenced by the gut and oral microbiota. Therefore, this project proposes to investigate the mechanisms of response to biologic agents, aiming to explore more precise treatment strategies, through the integration of single-cell transcriptomics, 16S rRNA, and other multi-omics technologies on tissue samples, feces, saliva, peripheral blood, etc., from IBD patients before and after treatment. This will involve integrating bioinformatics analysis and in vitro/in vivo functional validation to elucidate the roles of treatment-responsive cell subtypes and gut and oral microbiota in the inflammatory microenvironment of the intestine, with the aim of uncovering the mechanisms of biologic agent therapy and providing new clues for the development of next-generation drug targets.